With the development of displaying techniques, the number of pixels per inch in a display device increases, a distance between adjacent pixels decreases, and correspondingly, a ratio of the area of a pixel electrode over the area of the pixel decreases.
Reference may be made to FIG. 1, which schematically illustrates a principle of connections within the pixel of a conventional and common TFT (Thin Film Transistor) LCD (Liquid Crystal Display). As shown in FIG. 1, a gate electrode of a thin film transistor is connected to a gate line, and the thin film transistor is controlled via the gate line to be on or off. A drain electrode of the thin film transistor is connected to a data line, a source electrode of the thin film transistor is connected to a pixel electrode, and a driving signal is provided to the pixel electrode via the data line when the thin film transistor is turned on. A parasitic capacitor Cgs is generated between the gate electrode and the source electrode of the thin film transistor, i.e. the pixel electrode is connected to the gate line via the parasitic capacitor Cgs. A liquid crystal capacitor Clc and a storage capacitor Cst are connected in parallel between the pixel electrode and a common electrode. At instants when the thin film transistor is turned on and turned off, variation of a voltage of the gate line may affect a voltage of the pixel electrode via the parasitic capacitor Cgs, and a feed though voltage is generated on the pixel electrode, thereby affecting the quality of displayed images. A formula for calculating the feed though voltage is as follows:Vfeedthough=Vd2−Vd1=(Vg2−Vg1)*Cpg/(Cpg+Clc+Cst).
Vfeedthough represents the feed though voltage on the pixel electrode; Vd2 represents a voltage on the pixel electrode when the thin film transistor is turned off; Vd1 represents a voltage on the pixel electrode when the thin film transistor is turned on; Vg2 represents an output voltage of the gate line when the thin film transistor is turned off; Vg1 represents an output voltage of the gate line when the thin film transistor is turned on; Cpg represents a parasitic capacitance between the gate electrode and the source electrode of the thin film transistor; Clc represents a liquid crystal capacitance of the display device; and Cst represents a storage capacitance between the pixel electrode and the common electrode.
A formula for calculating the storage capacitance between the pixel electrode and the common electrode is: Cst=∈*S/d, where Cst represents the storage capacitance between the pixel electrode and the common electrode, ∈ represents a dielectric constant of a medium between the pixel electrode and the common electrode, S represents an overlapping area of the pixel electrode and the common electrode, and d represents a distance between the pixel electrode and the common electrode.
As can be seen from the above formula, the overlapping area of the pixel electrode and the common electrode may decrease as the area of the pixel electrode decreases, and the feed though voltage on the pixel electrode may increase correspondingly, thereby aggravating acoustic crosstalk and screen flickering occurring on the display device and affecting quality of displayed images.
Comparing with a display panel with high Pixels Per Inch (PPI, i.e., the number of pixels per inch), a display panel with high PPI includes a greater number of pixel units and has a smaller opening area of each pixel unit. Hence, the overlapping area of the pixel electrode and the common electrode in each pixel unit is significantly decreased, and accordingly, acoustic crosstalk and screen flickering are aggravated and the quality of displayed images is affected.